Wildlife research often necessitates methods for estimating the size of unknown wild animal populations and for tracking individual animals within those populations. These two goals may generally be referred to as “censusing” and “monitoring,” respectively.
Traditional methods of censusing and monitoring often involve invasive and costly approaches such as radio-telemetry (e.g., fitting a tracking device to an animal) or marking (e.g., ear-notching). These methods generally involve either direct physical handling of the animals or otherwise disturbing the animals in their natural habitat. Evidence suggests that such methods may have harmful effects on endangered species, including decreased fertility, reduced body weight, and ranging behavior. Furthermore, capturing an animal through physical or chemical immobilization may cause the animal stress, pain, fear, anxiety, physical injury, or even death.
Endangered species often are particularly desirable to census and monitor as they tend to have low or declining populations, and it is desirable to protect them in order to preserve biodiversity. It is therefore desirable to have a method of censusing and monitoring endangered species in a manner that is unobtrusive and harmless to the animals that are the subject of observation. Close observation from ground or aerial vehicles may allow observation of species without directly handling the animals. But, these methods are expensive and are still likely to involve creating an unnatural disturbance in the habitat of the animals that may negatively impact the animals. Furthermore, individual animals may not be easily identified and distinguished from others by mere observation alone.
Every species of animal has a unique foot anatomy, and each individual animal within a species has unique footprints. Accordingly, species of animals may be identified by examining a set of footprints or tracks (“tracking”). Tracking has long been a method used in hunting and wildlife research to locate a particular species of animal. While it is both cheap and unobtrusive, tracking is a difficult skill learned over time that cannot be readily imparted to wildlife researchers. Further, even experienced trackers may not be able to readily determine the individual identification, age-class, or sex of an animal within the species from merely observing tracks. Furthermore, to the extent a tracker may attempt to associate a set of tracks with an individual animal, the identification may be inherently unreliable as it requires the use of the tracker's memory for comparison to other sets of tracks. As such, digital photography may provide a suitable aid in advancing the use of animal tracks for identification purposes.